Apparatus for cutting exhaust system tubes

ABSTRACT

Apparatus is disclosed for cutting through exhaust system components, such as tubes of various sizes and the like, which includes a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool, an elongated cutting blade of the sabre saw type, and an attachment including a tube engaging structure pivotally mounted on the housing on the tool for movement with respect thereto between a tube receiving position and a cutting cycle completion position, a handle for enabling the operator to effect manual movement of the structure into the tube receiving position, the structure providing a tube receiving recess therein open in a direction toward the cutting teeth and free end of the blade when the structure is moved into the tube receiving position thereof so as to position the structure in operative relation with a tube and a spring connected with the structure for effecting a resiliently biased movement thereof from the tube receiving position into the cutting cycle completion position upon the manual release of the handle with a tube disposed in operative relation between the recess and the cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of the structure without engagement of the handle permitting the operator to support portions of the exhaust system which are cut during the operation.

llnited States Patent [191 Smeltzer et al.

[111 3,834,019 [451 Sept. 10, 1974 APPARATUS FOR CUTTING EXHAUST SYSTEM TUBES [75] Inventors: Paul Smeltzer, Naperville; David A.

Daneck, Chicago Heights, both of I11.

[73] Assignee: Maremont Corporation, Chicago,

Ill.

22 Filed: Nov. 22, 1972 21 App]. No.: 308,785

[52] US. Cl. 30/92, 30/378 [51] Int. Cl B26d 7/02 [58] Field of Search 30/92, 166, 166 A, 378,

Primary ExaminerAl Lawrence Smith Assistant Examiner-J. C. Peters Attorney, Agent, or FirmCushman, Darby & Cushman [57] ABSTRACT Apparatus is disclosed for cutting through exhaust system components, such as tubes of various sizes and the like, which includes a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool, an elongated cutting blade of the sabre saw type, and an attachment including a tube engaging structure pivotally mounted on the housing on the tool for movement with respect thereto between a tube receiving position and a cutting cycle completion position, a handle for enabling the operator to effect manual movement of the structure into the tube receiving position, the structure providing a tube receiving recess therein open in a direction toward the cutting teeth and free end of the blade when the structure is moved into the tube receiving position thereof so as to position the structure in operative relation with a tube and a spring connected with the structure for effecting a resiliently biased movement thereof from the tube receiving position into the cutting cycle completion position upon the manual release of the handle with a tube disposed in operative relation between the recess and the cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of the structure without engagement of the handle permitting the operator to support portions of the exhaust system which are cut during the operation.

12 Claims, 4 Drawing Figures APPARATUS FOR CUTTING EXHAUST SYSTEM TUBES This invention relates to the cutting of exhaust system tubes and the like and more particularly to an attachment for a conventional portable power operated sabre saw tool for facilitating the positioning of exhaust system tubes of different sizes in operative relation with the cutting blade and the cutting movement of the blade therethrough.

It is currently standard procedure for exhaust system installers to remove rusted and worn exhaust components from vehicles with the use of an oxy-acetylene cutting torch. The problems incident to the use of cutting torches of this type have become more acute in recent months and years. Probably the most serious problem is the increasing awareness of the hazards which are presented as a result of utilizing a fire of such intensity close to the combustible products which are always in close proximity to the exhaust systems of vehicles within the installation locations. The potential fire hazards involved are now sufficiently recognized that many insurance companies provide increase in rates where such torches are used. In addition to these cost problems, in many installations, the use of such torches, while effecting savings, as compared with other known cutting procedures, does involve the expenditure of considerable time, particularly in those situations where the installation volume is sufficiently low as to require the installer to turn on the gas, strike and adjust the torch flame prior to making the cuts for each installation. Moreover, the cut made by such torch is not as clean as is capable of being achieved with other cutting procedures.

Accordingly, it is an object of the present invention to substantially alleviate the problems enunciated above incident to the use of conventional oxyacetylene cutting torches in removing exhaust system components from vehicles. In accordance with the principles of the present invention, this objective is obtained by utilizing a conventional power-operated portable sabre saw and providing an attachment for such tool which facilitates the positioning of exhaust system tubes of different sizes in operative relation with the cutting blade thereof and the cutting movement of the blade therethrough. But utilizing these principles of the present invention, the fire hazards incident to the use of oxy-acetylene torches is completely eliminated, the start-up time required in lighting such torches is eliminated, and a better and cleaner cut in the tubes can be obtained thus enabling a greater degree of salvage of the components of the exhaust system of the vehicle.

Another object of the present invention is the provision of an attachment of the type described which is capable of accomplishing the necessary cutting action in a minimum period of time and which provides for a resilient feeding action of the cutting blade through the exhaust system tubes while the cutting blade is positively retained in operative cutting relation to the tube without necessity of the operator effecting manual movement of the attachment thus providing the operator freedom of use of one hand for supporting the exhaust system components during the cutting action.

Another object of the present invention is the provision of an attachment of the type described which is simple in construction, efficient in operation and economical to manufacture and maintain.

These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.

The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.

IN THE DRAWINGS:

FIG. 1 is a perspective view of an apparatus embodying the principles of the present invention, showing the parts thereof in a pipe receiving position;

FIG. 2 is a side elevational view of the apparatus, showing the parts in a cutting cycle completion position;

FIG. 3 is view similar to FIG. 2, showing the parts in an intermediate cutting position; and

FIG. 4 is an enlarged, fragmentary sectional view taken along the line 44 of FIG. 3.

Referring now more particularly to the drawings, there is shown therein an apparatus, generally indicated at 10, for cutting through exhaust system components, such as tubes of various sizes and the like. The apparatus includes a conventional power-operated portable tool, generally indicated at 12, of the type including a housing 14 having a blade receiving member 16 mounted therein for continuous reciprocating movement during the power operation of the tool. As indicated, the tool 12 may be of any conventional construction, the drawings illustrating a tool manufactured by the Milwaukee Tool Company and merchandised under the trademark SAWZALL, Model No. 6505. It will be understood that the tool 12 includes the usual electrical motor (not shown) within the housing 14 which, through the usual power transmission (not shown) serves to impart continuous reciprocating movement to the blade receiving member 16 in response to the engagement of an actuating trigger 18 by an operator grasping a handle 20 provided by the housing 14.

The apparatus 10 also includes a conventional cutting blade, generally indicated at 22, including a free end 24 and a remote end 26 which is adapted to be fixedly attached to the outwardly extending end of the blade receiving member 16, by any suitable means, such as a nut and clip assembly 27. The blade 22 also includes a series of cutting teeth 28 extending along one longitudinal edge thereof between the ends 24 and 26. In accordance with conventional practice, the cutting teeth 8 are shaped so as to effect a cutting action during the reciprocating movement thereof in one direction. In the embodiment shown, the cutting teeth 28 are shaped to provide a cutting action during the movement of the blade in a direction inwardly toward the housing 14 of the tool 12.

The apparatus 10 also includes an attachment, generally indicated at 30, which functions to facilitate the positioning of workpieces, such as exhaust system tubes of different sizes, in operative relation with the cutting blade 22 and the cutting movement of the blade through the tubes. As best shown in FIG. 1, the attachment 30 comprises a tube engaging structure, generally indicated at 32 and a mounting assembly, generally indicated at 34, adapted to be detachably fixedly secured to the housing 14 of the tool 12, for mounting the tube engaging structure 32 thereon for movement with respect thereto between a tube receiving position (FIG. 1) and a cutting cycle completion position (FIG. 2). In

the preferred embodiment shown, the mounting assembly 34 serves to mount the tube engaging structure 32 for pivotal movement between the aforesaid positions. It will be understood, however, that other known types of movement may be utilized in lieu of the preferred pivotal movement. The attachment 30 also includes manually engageable means preferably in the form of a handle 36 or the like adapted to be manually engaged by an operator for the purpose of effecting manual movement of the tube engaging structure into its tube receiving position, as shown in FIG. 1.

The tube engaging structure 32 provides tube receiving recess means, generally indicated at 38, which, as best shown in FIG. 1, is open in a direction toward the cutting teeth 28 and free end 24 of the blade 22 when the tube engaging structure 32 is disposed in its tube receiving position. It will be noted that the recess means 38 is spaced from the cutting teeth and the free end of the blade a distance sufficient to enable the operator to position the tube engaging structure 32 in operative relation with a tube with the latter extending transversely between the recess means 38 and the cutting teeth 28 of the blade 22.

The attachment 30 also includes spring means, preferably in the form of a coil spring 40, which is operatively connected between the housing 14 and the tube engaging structure 32 for effecting a resiliently biased movement of the latter from the tube receiving position thereof, such as shown in FIG. 1, into the cutting cycle completion position, such as shown in FIG. 2, upon the manual release of the handle 36 by the operator with a tube disposed in operative relation between the recess means 38 and the cutting blade 22 so that the operative movement of the blade transversely cuts the tube during the resiliently biased movement of the tube engaging structure without engagement of the handle by the operator.

The tube engaging structure 32 may assume any desired configuration, however, in the preferred embodiment illustrated in the drawings, the structure is made up of a pair of sheet metal members of mirror image configuration. As best shown in FIG. 1, the members include a pair of parallel transversely spaced tube engaging panel portions 42 each having inwardly bent tabs 44 formed on the outer end thereof and the lower central edges thereof, the tabs 44 being disposed in edge abutting relation and suitably rigidly secured together, as by welding or the like. The members also include mounting portions 46 extending inwardly toward the tool 12 and spaced apart a distance greater than the spacing between the tool engaging portions 42 so as to extend on opposite sides of the nose portion of the housing 14.

The mounting assembly 34 includes a pair of mounting plates 48 of a size to engage within recesses 50 formed in the sides of the nose portion of the housing 14. Associated with one of the mounting plates 48 is a stop member 52 in the form of a plate or the like having its upper end bent outwardly to provide a stop lug 54 adapted to be engaged by the adjacent upper surface of the associated mounting portion 46 of the structure 32 when the latter is disposed in the cutting cycle completion position thereof, as shown in FIG. 2. The mounting plates 48 and the stop member 52 are detachably fixedly secured within the recesses 50 of the housing 14, by any suitable means, such as bolts 56 or the like.

The mounting assembly 34 also includes a pair of pin members 58 suitably carried by the plates 48 and pivotally receiving the mounting portions 46 of the tube engaging structure 32. The pin members 58, as shown, are preferably in the form of exteriorly shouldered tubular elements, the mounting portions 46 being provided with apertures 60 of a size to engage over the reduced exterior portions of the tubular elements. As best shown in FIG. 4, the pin members are detachably secured to the mounting plates 48, as by bolts 62 or the like, extending through the interior of the pin members 58 into threaded engagement with appropriately threaded openings formed in the inner ends of the mounting plates 48.

The handle 36, as shown, is preferably in the form of a molded handle grip of resilient or plastic material of generally hollow configuration. The handle grip is fixedly attached to the structure 32 by any suitable means which, as shown, is preferably in the form of a pair of metal straps 64 having their upper end portions rigidly secured to the inner surfaces of the mounting portions 46, as by welding or the like, and their lower portions bent inwardly into abutting engagement and engaged within the hollow interior of the handle grip 36.

As best shown in FIGS. 1-3, the tube receiving recess means 38 is preferably defined by edge surfaces of the mounting portions 42, indicated at 66 and 68, which diverge with respect to each other in the direction in which the recess means 38 opens. The surfaces 66 are preferably straight and face in a direction generally opposed to the direction of the cutting teeth 28 of the blade 22. The size of the tube receiving recess provided by the surfaces 66 and 68 is such as to accommodate tubes within a range of 1 inch to 2-% inches, which range includes exhaust system component tubes embodied in most vehicles presently in existence. The surface 68 are likewise preferably straight, the inner edge ends thereof merging with the straight surfaces 66 with suitable arcuate fillet surfaces or the like.

In the preferred embodiment shown, the spring 40 is in the form of a conventional coil spring having the ends thereof connected to the inner ends of the mounting portions 46 inwardly of the pivot pins 58, as indicated at 70. The central portion of the coil spring 40 is extended over the portion of the tool housing 14 extending in the direction of movement of the ends 70.

With the preferred arrangement shown, the spring 40 is easily moved into an inoperative blade changing position shown in dotted lines in FIG. 2. In this position, the central portion of the spring extends over the forward portion of the housing 14 in a direction perpendicular to the direction of movement of the ends 70. It will be understood that since the forward portion of the housing 14 is spaced from the ends 70 a distance less than the spacing of the lower portion of the housing 14 from the ends, the spring 40 will not apply resilient pressure to the structure 32 when the spring is disposed in its inoperative blade changing position. In this position the operator is enabled to move the structure 32 into the tube receiving position, as shown in FIG. 1, in which position it will be retained without bias permitting the operator convenient access to the volt 27 which serves to detachably secure the blade 22 to the blade receiving member 16.

It will be understood that the spring 40 may be of any conventional configuration so long as the essential functional characteristics are provided. These characteristics are that the spring must exert sufficient force on the structure 32 to effect a feeding action of the blade through the tube without the necessity of the operator applying pressure to the handle 36. Conversely, the spring should not be so heavy as to provide a force which would cause some slight buckling to occur in the saw blade or to render the attachment difficult or tiring to move manually against the action of the spring. In the preferred embodiment shown, the spring 40 is of a coil configuration having a spring rate of 4.2 pounds per inch and a free length of 5 inches. In the embodiment shown, the spring provides a minimum load measured with the structure 32 in its cutting cycle completion position, as shown in FIG. 2, of approximately 5.5 pounds and a maximum load measured with the structure 32 operating against a 2 /2 inch diameter tube at the initially engaged position thereof of approximately 14 pounds.

The operation of the present invention is believed apparent from the description set forth above. To reiterate the cycle of operation, it will be noted that the spring 40 normally urges the structure 32 into a cutting cycle completion position such as shown in FIG. 2 wherein the stop lug 54 is engaged by the mounting portions 46 of the structure 32. When it is desired to utilize the apparatus 10, the operator grasps the handle of the tool with one hand and the handle 36 of the attachment with the other and by moving the latter rearwardly effects a pivotal movement of the structure 32 about the axis provided by the pivot pins 58 from the cutting cycle completion position of FIG. 2 into the tube receiving position shown in FIG. ll. In this regard, it will be noted that the engagement of the handle mounting straps 64 with the housing 14 of the tool serves as a stop to limit the movement of the structure 32 into the tube receiving position as shown in FIG. 1. In this position, it will be noted that the recess means 38 is open in a direction toward the cutting teeth 28 of the cutting blade and the free end 24 thereof. With the apparatus disposed in this position, the operator simply moves the apparatus with respect to the tube being out until the tube is disposed in a position between the recess means 38 and the cutting blade 22. The operator then releases the handle 36 permitting spring 40 to move the structure 32 from the tube receiving position toward a cutting cycle completion position. The force of the spring serves to resiliently urge the tube engaged with the surfaces 66 and 68 toward the cutting teeth 28. The operator then actuates the trigger 18 causing the cuttng blade 22 to continuously reciprocate. It will be noted that the cutting stroke of the blade is during the movement toward the tool housing 14. Movement of the tube in response to the cutting strokes of the blade is resisted by engagement of the surfaces 66 which at all times face in a direction generally opposed to the cutting stroke. Moreover, it will be noted that as the cutting proceeds, surfaces 66 will move through an intermediate position, as shown in FIG. 3, wherein the surfaces are essentially perpendicular with the direction of the cutting stroke. This disposition of the surfaces 66 of the recess means 38 materially aids in retaining the tube in cutting engagement with the blade It will be understood that while the disposition of the surfaces 66 as shown and described above are preferred when a conventional cutting blade 22 is used,

the present invention also contemplates, in its broadest aspects, the disposition of the surfaces 66 at different angles and curvatures for accommodating different blade constructions such as, for example, the blade construction and contours as described in commonly assigned patent application Ser. No. 308,788, filed concurrently herewith in the name of Sellers B. McNally, the disclosure of which is hereby incorporated by reference into the present specification.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiment has been shown and described for the purpose of illustrating the functional'and structural principles of this invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is:

I. For use with a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool and an elongated cutting blade of the type including a free end, an opposite end adapted to be attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one edge thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, an attachment for said tool for facilitating the positioning of workpieces, such as exhaust system tubes of different sizes, in operative relation with the cutting blade and the cutting blade and the cutting movement of the blade therethrough, said attachment comprising:

a tube engaging structure,

means for pivotally mounting said structure on the housing of the tool for movement with respect thereto about a pivotal axis extending generally perpendicular to the direction of reciprocating movement of the blade receiving member of the tool between a tube receiving position and cutting cycle completion position,

manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position,

said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of the blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to position said structure in operative relation with a tube with the latter extending transversely between said recess means and the cutting teeth of the blade,

said recess means being defined by longitudinally spaced surfaces which diverge in the direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and

spring means operatively connected with said structure for effecting a resiliently biased movement thereof from said tube receiving position into said cutting cycle completion position upon the manual release of said manually engageable means with a tube disposed in said operative relation between said recess means and said cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means, said manually engageable means comprising a handle rigidly secured to said structure and disposed at a position outwardly of the pivotal axis of said structure a distance greater than said recess means for enabling an operator manually engaging the same to effect movement of said structure into said tube receiving position against the bias of said spring means.

2. For use with a power operated portable tool of the type including a housing having blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool and an elongated cutting blade of the type including a free end, an opposite end adapted to be attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one edge thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, an attachment for said tool for facilitating the positioning of workpieces, such as exhaust system tubes of different sizes, in operative relation with the cutting blade and the cutting movement of the blade therethrough, said attachment comprising:

a tube engaging structure,

means for mounting said structure on the housing of the tool for movement with respect thereto between a tube receiving position and cutting cycle completion position,

manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position,

said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of the blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to position said structure in operative relation with a tube with the latter extending transversely between said recess means and the cutting teeth of the blade,

said recess being defined by longitudinally spaced surfaces which diverge in the direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and spring means operatively connected with said structure for effecting a resiliently biased movement thereof from said tube receiving position into said cutting cycle completion position upon the manual release of said manually engageable means with a tube disposed in said operative relation between said recess and said cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means, said structure including a pair of members having transversely spaced tube receiving portions disposed to move on opposite sides of the cutting blade during the movement of said structure adjacent and into said cutting cycle completion position, said surfaces resisting cutting movement of the blade constituting generally straight parallel surfaces on said tube engaging portions extending perpendicular to the cutting teeth edge of the blade when said structure is disposed in an intermediate position between said tube receiving position and said cutting cycle completion position.

3. For use with a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool and an elongated cutting blade of the type including a free end, an opposite end adapted to be attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one edge thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, an attachment for said tool for facilitating the positioning of workpieces, such as exhaust system tubes of different sizes, in operative relation with the cutting blade and the cutting movement of the blade therethrough, said attachment comprising:

a tube engaging structure,

means for mounting said structure on the housing of the tool for movement with respect thereto between a tube receiving position and cutting cycle completion position,

manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position,

said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of the blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to position said structure in operative relation with a tube with the latter extending transversely between said recess means and the cutting teeth of the blade,

said recess means being defined by longitudinally spaced surfaces which diverge in the direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and

spring means operatively connected with said structure for effecting a resiliently biased movement thereof from said tube receiving position into said cutting cycle completion position upon the manual release of said manually engageable means with a tube disposed in said operative relation between said recess means and said cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means, said structure including a pair of members having transversely spaced tube receiving portions disposed to move on opposite sides of the cutting blade during the movement of said structure adjacent and into said cutting cycle completion position, said members including mounting portions formed of said tube engaging portions and spaced apart a distance greater than the spacing between said tube engaging portions.

4. An attachment as defined in claim 3 wherein said structure mounting means includes a mounting assembly adapted to be fixedly attached to said tool housing including pin members pivotally receiving said mounting portions.

5. An attachment as defined in claim 4 wherein said members are of sheet metal construction each having inwardly bent tabs disposed outwardly of the free end of the cutting blade and rigidly secured together.

6. An attachment as defined in claim 4 wherein said spring means includes a coil spring having the ends thereof connected with said mounting portions inwardly of said pivot pin members and the central portion thereof adapted to be movable between an operative position in engagement with a portion of the tool housing spaced from coil spring ends generally in the direction of movement thereof with said structure and a blade changing position in engagement with a portion of the housing spaced a lesser distance from the coil spring ends generally perpendicular to the direction of movement thereof with said structure.

7. An attachment as defined in claim 1 wherein said structure mounting means includes a stop member for engaging said structure when the latter moves into said cutting cycle completion position under the action of said spring means.

8. Apparatus for cutting through exhaust system components, such as tubes of various sizes and the like, comprising: a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool, an elongated cutting blade including a free end, an opposite end attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one end thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, a tube engaging structure, means mounting said structure on said tool for movement with respect thereto between a tube receiving position and a cutting cycle completion position, manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position, said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of said blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to position said structure in opera tive relation with a tube with the latter extending transversely between said recess means and the cutting teeth of said blade, said recess means being defined by longitudinally spaced surfaces which diverge in a direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and spring means continuously operatively connected with said structure and said housing for effecting a resiliently biased movement of said structure from said tube receiving position into said cutting cycle completion position upon a manual release of said manually engageable means with a tube disposed in said operative relation between said recess means and said cutting blade so that the operative movement of said blade transversely cuts the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means.

9. Apparatus as defined in claim 8 wherein said structure mounting means includes pin means for pivotally mounting said structure on said housing for movement about an axis extending generally perpendicular to the direction of reciprocating movement of said blade receiving member.

10. Apparatus as defined in claim 9 wherein said spring means includes a coil spring having the ends thereof connected with said structure on opposite sides of said housing inwardly of the pivotal axis thereof and the central portion thereof between an operative position in engagement with a portion of said housing spaced from said coil spring ends generally in the direction of movement thereof with said structure and a blade changing position in engagement with a portion of said housing spaced a lesser distance from the coil spring ends generally perpendicular to the direction of movement thereof with said structure.

11. Apparatus as defined in claim 10 wherein said structure mounting means further includes a stop member fixed with respect to said housing for engaging said structure when the latter moves into said cutting cycle completion position under the action of said spring means.

12. Apparatus as defined in claim 11 wherein said manually engageable means comprises a handle rigidly secured to said structure. 

1. For use with a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool and an elongated cutting blade of the type including a free end, an opposite end adapted to be attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one edge thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, an attachment for said tool for facilitating the positioning of workpieces, such as exhaust system tubes of different sizes, in operative relation with the cutting blade and the cutting blade and the cutting movement of the blade therethrough, said attachment comprising: a tube engaging structure, means for pivotally mounting said structure on the housing of the tool for movement with respect thereto about a pivotal axis extending generally perpendicular to the direction of reciprocating movement of the blade receiving member of the tool between a tube receiving position and cutting cycle completion position, manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position, said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of the blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to position said structure in operative relation with a tube with the latter extending transversely between said recess means and the cutting teeth of the blade, said recess means being defined by longitudinally spaced surfaces which diverge in the direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and spring means operatively connected with said structure for effecting a resiliently biased movement thereof from said tube receiving position into said cutting cycle completion position upon the manual release of said manually engageable means with a tube disposed in said operative relation between said recess means and said cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means, said manually engageable means comprising a handle rigidly secured to said structure and disposed at a position outwardly of the pivotal axis of said structure a distance greater than said recess means for enabling an operator manually engaging the same to effect movement of said structure into said tube receiving position against the bias of said spring means.
 2. For use with a power operated portable tool of the type including a housing having blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool and an elongated cutting blade of the type including a free end, an opposite end adapted to be attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one edge thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, an attachment for said tool for facilitating the positIoning of workpieces, such as exhaust system tubes of different sizes, in operative relation with the cutting blade and the cutting movement of the blade therethrough, said attachment comprising: a tube engaging structure, means for mounting said structure on the housing of the tool for movement with respect thereto between a tube receiving position and cutting cycle completion position, manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position, said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of the blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to position said structure in operative relation with a tube with the latter extending transversely between said recess means and the cutting teeth of the blade, said recess being defined by longitudinally spaced surfaces which diverge in the direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and spring means operatively connected with said structure for effecting a resiliently biased movement thereof from said tube receiving position into said cutting cycle completion position upon the manual release of said manually engageable means with a tube disposed in said operative relation between said recess and said cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means, said structure including a pair of members having transversely spaced tube receiving portions disposed to move on opposite sides of the cutting blade during the movement of said structure adjacent and into said cutting cycle completion position, said surfaces resisting cutting movement of the blade constituting generally straight parallel surfaces on said tube engaging portions extending perpendicular to the cutting teeth edge of the blade when said structure is disposed in an intermediate position between said tube receiving position and said cutting cycle completion position.
 3. For use with a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool and an elongated cutting blade of the type including a free end, an opposite end adapted to be attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one edge thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, an attachment for said tool for facilitating the positioning of workpieces, such as exhaust system tubes of different sizes, in operative relation with the cutting blade and the cutting movement of the blade therethrough, said attachment comprising: a tube engaging structure, means for mounting said structure on the housing of the tool for movement with respect thereto between a tube receiving position and cutting cycle completion position, manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position, said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of the blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to position said structure in operative relation wIth a tube with the latter extending transversely between said recess means and the cutting teeth of the blade, said recess means being defined by longitudinally spaced surfaces which diverge in the direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and spring means operatively connected with said structure for effecting a resiliently biased movement thereof from said tube receiving position into said cutting cycle completion position upon the manual release of said manually engageable means with a tube disposed in said operative relation between said recess means and said cutting blade so that the operative movement of the blade will transversely cut the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means, said structure including a pair of members having transversely spaced tube receiving portions disposed to move on opposite sides of the cutting blade during the movement of said structure adjacent and into said cutting cycle completion position, said members including mounting portions formed of said tube engaging portions and spaced apart a distance greater than the spacing between said tube engaging portions.
 4. An attachment as defined in claim 3 wherein said structure mounting means includes a mounting assembly adapted to be fixedly attached to said tool housing including pin members pivotally receiving said mounting portions.
 5. An attachment as defined in claim 4 wherein said members are of sheet metal construction each having inwardly bent tabs disposed outwardly of the free end of the cutting blade and rigidly secured together.
 6. An attachment as defined in claim 4 wherein said spring means includes a coil spring having the ends thereof connected with said mounting portions inwardly of said pivot pin members and the central portion thereof adapted to be movable between an operative position in engagement with a portion of the tool housing spaced from coil spring ends generally in the direction of movement thereof with said structure and a blade changing position in engagement with a portion of the housing spaced a lesser distance from the coil spring ends generally perpendicular to the direction of movement thereof with said structure.
 7. An attachment as defined in claim 1 wherein said structure mounting means includes a stop member for engaging said structure when the latter moves into said cutting cycle completion position under the action of said spring means.
 8. Apparatus for cutting through exhaust system components, such as tubes of various sizes and the like, comprising: a power operated portable tool of the type including a housing having a blade receiving member mounted therein for continuous reciprocating movement during the power operation of the tool, an elongated cutting blade including a free end, an opposite end attached to said blade receiving member, and a series of cutting teeth extending longitudinally along one end thereof between the ends thereof shaped to cut in response to reciprocating movement thereof in one direction, a tube engaging structure, means mounting said structure on said tool for movement with respect thereto between a tube receiving position and a cutting cycle completion position, manually engageable means for enabling an operator to manually effect movement of said structure into said tube receiving position, said structure providing tube receiving recess means therein open in a direction toward the cutting teeth and free end of said blade when said structure is moved into said tube receiving position by the manual movement of said manually engageable means a distance sufficient to enable the operator to posItion said structure in operative relation with a tube with the latter extending transversely between said recess means and the cutting teeth of said blade, said recess means being defined by longitudinally spaced surfaces which diverge in a direction in which the recess means opens so as to be operable to receive therebetween and engage tubes of various diameter size, certain of said surfaces facing generally in a direction opposed to the direction of cut of the cutting teeth to resist movement of the tube in the direction of cutting movement when said cutting teeth are in cutting engagement therewith, and spring means continuously operatively connected with said structure and said housing for effecting a resiliently biased movement of said structure from said tube receiving position into said cutting cycle completion position upon a manual release of said manually engageable means with a tube disposed in said operative relation between said recess means and said cutting blade so that the operative movement of said blade transversely cuts the tube during the aforesaid resiliently biased movement of said structure without engagement of said manually engageable means.
 9. Apparatus as defined in claim 8 wherein said structure mounting means includes pin means for pivotally mounting said structure on said housing for movement about an axis extending generally perpendicular to the direction of reciprocating movement of said blade receiving member.
 10. Apparatus as defined in claim 9 wherein said spring means includes a coil spring having the ends thereof connected with said structure on opposite sides of said housing inwardly of the pivotal axis thereof and the central portion thereof between an operative position in engagement with a portion of said housing spaced from said coil spring ends generally in the direction of movement thereof with said structure and a blade changing position in engagement with a portion of said housing spaced a lesser distance from the coil spring ends generally perpendicular to the direction of movement thereof with said structure.
 11. Apparatus as defined in claim 10 wherein said structure mounting means further includes a stop member fixed with respect to said housing for engaging said structure when the latter moves into said cutting cycle completion position under the action of said spring means.
 12. Apparatus as defined in claim 11 wherein said manually engageable means comprises a handle rigidly secured to said structure. 